My Jeep® uses what is commonly called a 7-wire turn signal system
since it uses 7 wires to work. There are simpler systems out there but they are
pretty easy to figure out.

Click this link or the diagram below to see a Flash
animation of a typical turn signal system (you'll need to have Macromedia's Flash player
installed). Click the left button for a left turn signal, the right button for a
right turn, and the 4-way button for 4-way flashers. Click the Canel button to
cancel the signals. Click the brake pedal with the mouse and hold the mouse
button down to "apply" the brakes. Release the button to turn the
brakes off. This will let you see how one signal can flash while the brake light
comes on on the other side.

This will show you how one of these things works and should help if
you are trying to troubleshoot your system. Many folks don't understand that their
turn signal switch can cause problems like brake lights that don't work right. View
the animation and you'll see why that's the case. The brake lights are routed right
through the turn signal switch. The diagram below shows the contacts in position for
a right turn with no brakes applied:

Below are some notes I made when working on my turn signal system.

Total amperage for 4-way blinked lights is 11.7A.
This breaks down into the following:

Front: 2A each lamp, 4A total

Rear: 3A each side (2 lamps per taillight, 4 lamps total), 6A total
(this spec is for my military style tail lights).

Signal Lamp in Sparton: 1A

Flasher fuse: 9A (used 15A for 4-way test)

Flasher: 550 3-prong

Sparton Signal unit: 7-wire system

One side blink: 5A including Sparton lamp

4-way blink: 11A including Sparton lamp

All amperages shown are approximate, however, 4-way blinked system
11.7A total and front lamp 2.1A readings were taken with Fluke® DMM and are fairly accurate.

Sunday, August 25 2002 6:35 PM

Replaced the ancient "Tung-Sol" 550 flasher can with a fancy little unit from
AutoZone. The replacement unit looks like it has a real relay inside of it and has some
heft to it. Standard cans were $2 and the fancy one was only $6 so I figured I might as
well try it. Supposedly will last 10 times longer than the regular units.

I don't know if it will last longer (I hope so), BUT, it has *far better* flashing
characteristics with a very steady normal flash rate. Old unit flashed very fast. Only
problem with this better unit is it flashes correctly even if you have a lamp burned out,
there will be no increase in flash speed or change of sound like the regular flasher cans
if a lamp burns out.

Replaced original Sparton turn signal unit with the "modern" equivalent: the
Signal-Stat® model 900. Had to give up self-cancelling operation (which didn't work well
on the old Sparton anyway so it's not like I'll miss it) but I gained 4-way flashing and
smooth reliable switching with the new one. Unknown if an NOS Sparton would have worked
better. Probably would have worked OK but they are $80 online and I got the Signal-Stat
for $46 on sale at NAPA. This was cheaper than J.C. Whitney sells the Signal-Stats for
with shipping.

When installing the Signal-Stat, I added a 46 ohm resistor to the pilot light lead to
extend the lamp life of the lamp (grain of wheat?) they use for an indicator. Should have
been more like a 30 ohm or so, but 46 was all I had and I do NOT want to have to replace
that bulb as long as I own the Jeep. Also added a ground wire into their harness and moved
the pilot light wire from a bad location outside the case to inside the case and harness.

Note that YOU MUST INSTALL A HIGHER CAPACITY FUSE TO RUN THE 4-WAY FUNCTION.
I removed the existing 9A fuse and put in a 15A fuse before running the 4-way
flasher circuit. This was not mentioned anywhere in the Signal-Stat instructions. Kind of
an important omission. However, I was already aware of this problem from my previous amp
readings with the meter (see above). Even with the new flasher can and smaller(?) grain of
wheat(?) bulb in the Signal-Stat, total 4-way amperage still reads around 10.5A, and
that's 1.5A over the 9A original fuse. We would have had a positive smoke test for sure.

By the way, the new flasher can is rated at 25A max total. I should be able to add side
markers and/or trailer lights in the future without a problem. I used a regular hose clamp
to fasten it to the steering column instead of the very flimsy-looking setup they give
you.

The Jeep's flasher harness color codes* are as follows:

LF = single yellow wire

LR= single green wire

RF = dark grey wire in 3-wire plug

RR = orange wire in 3-wire plug

brake switch power = light grey wire in 3-wire plug

flasher load: white wire to flasher socket

flasher pilot: black wire to flasher socket

The Signal-Stat's harness color codes* are as follows:

LF = green wire

LR= grey wire

RF = red wire

RR = black wire

brake switch power = grey wire with black stripe

flasher load: yellow wire

flasher pilot: sky blue wire

Therefore, the color* table between the Signal-Stat harness to Jeep
harness is as follows:

LF = green to yellow

LR= grey to green

RF = red to dark grey

RR = black to orange

brake switch power = grey/black to light grey

flasher load: yellow to white

flasher pilot: sky blue to black

*Keep in mind your color codes could be completely different, so be
sure to check yours for differences.